A three-dimensional temperature field reconstruction method applied to low-temperature and acoustic wave cooperative fire extinguishing

Abstract

The application discloses a three-dimensional temperature field reconstruction method applied to low-temperature and acoustic wave cooperative fire extinguishing, relates to the technical field of low-temperature and acoustic wave cooperative fire extinguishing, and first acquires flame boundary prior information to construct a physical prior field, and adjusts the grid size automatically according to the physical prior field, so as to match the three-dimensional temperature field boundary grid with dynamic temperature gradient changes, then constructs a weighted matrix based on path signal-to-noise ratio, gives higher reconstruction weight to a path with higher signal-to-noise ratio, and highlights the application of reliable data and ignores noise data in the iterative solving process, meanwhile, in the iterative inversion reconstruction, a mixed regularization function of flame temperature gradient distribution characteristics and temperature smooth distribution characteristics is designed, the unique large gradient structure and smooth background structure of the flame temperature field are fully applied in the inversion, and finally, a high-precision three-dimensional temperature field of the flame is reconstructed, so that the accurate low-temperature medium application amount and acoustic wave parameter design amount are calculated to realize high-precision cooperative fire extinguishing.

Description

Technical Field

[0001] This invention relates to the field of cryogenic and acoustic synergistic fire suppression technology, and particularly to a three-dimensional temperature field reconstruction method, system, equipment and medium for cryogenic and acoustic synergistic fire suppression. Background Technology

[0002] Currently, for fire protection in fields such as data centers, precision instruments, and cultural heritage sites, inert gas (such as IG-541) fire extinguishing systems are mainly used to achieve the effect of no secondary pollution. Although this gas is clean, the system is complex, costly, and the speed of suppressing open flames needs to be improved. Acoustic fire extinguishing, as an emerging technology, uses sound pressure to disturb the flame combustion zone, periodically pushing the flame away from the combustible material and interfering with the heat cycle between the flame and fuel to extinguish the fire. It has advantages such as reusability, low cost, and relatively simple equipment, but its main bottlenecks are the effective range, energy efficiency, and the sound power required for practical application. Cryogenic technology (such as liquid nitrogen) is often used for rapid cooling, but its efficiency may be insufficient and the cost may be high when used alone for fire extinguishing, making it difficult to directly extinguish flames by cooling. Therefore, at present, cryogenic technology is often combined with acoustic fire extinguishing to solve the problems existing in inert gas fire extinguishing.

[0003] Currently, when combining cryogenic technology and acoustic extinguishing technology for fire suppression, there are several issues to consider. Acoustic extinguishing technology has limitations in effective operating distance, energy efficiency, and the determination of required acoustic power, while cryogenic technology has limitations in cooling efficiency. Generally, infrared thermal imagers are used to monitor the temperature of the fire scene first. However, the temperature distribution of the fire scene changes rapidly over time, while infrared thermal imagers can only acquire the static two-dimensional projected temperature distribution of the fire scene. Furthermore, the flame's own radiation and high-temperature smoke cause strong interference to infrared detection, making it difficult to analyze the three-dimensional structure of the flame in the depth direction and to reflect the dynamic changes of the three-dimensional temperature field of the flame in real time.

[0004] To address the problem that current two-dimensional temperature fields cannot accurately reflect the dynamic changes of the three-dimensional temperature field of flames in real time, researchers have introduced Tunable Laser Absorption Spectrometry Tomography (TDLAS) technology and employed algorithms such as Algebraic Reconstruction Algorithm (ART) and Filtered Back Projection (FBP) to reconstruct the three-dimensional temperature field. However, these conventional reconstruction algorithms typically assume that the reconstruction area is divided into uniform grids. In actual fires, there is a huge temperature gradient at the interface between the flame and the air, and uniform grids are difficult to match dynamic temperature gradient changes. Furthermore, conventional reconstruction algorithms utilize measurement data from all laser paths simultaneously and reconstruct the three-dimensional physical field of the flame through mathematical inversion. However, in actual fires, laser path measurement data passing through high-temperature smoke is often affected by smoke scattering and turbulence disturbances. Without differentiation, this often leads to artifacts or errors in the temperature field. Moreover, mathematical inversion methods only utilize a general inversion environment and fail to fully utilize the inherent physical characteristics of the flame temperature field. Ultimately, this results in a large error between the reconstructed three-dimensional physical field and the dynamic changes of the flame in the actual fire. Consequently, the design values ​​for the amount of cryogenic medium applied and the acoustic parameters deviate from actual requirements, making it difficult to achieve high-precision coordinated fire suppression. Summary of the Invention

[0005] This invention provides a three-dimensional temperature field reconstruction method for combined cryogenic and acoustic fire suppression, which can solve the problems existing in the prior art.

[0006] This invention provides a three-dimensional temperature field reconstruction method for combined cryogenic and acoustic fire suppression. Multiple tunable diode lasers and corresponding photodetectors are arranged in different directions of the combined fire suppression device. The diode lasers emit laser light to scan the flame, which is then received by the photodetectors. The reconstruction method includes the following steps: Infrared thermal imagers are used to collect and fit the two-dimensional temperature field of a flame to obtain prior information of the flame boundary. Based on the prior information of the flame boundary, a physical prior field characterizing the degree of drastic change in flame temperature is constructed. According to the physical prior field, non-uniform adaptive meshing of the three-dimensional temperature field of the flame is performed to obtain the boundary mesh of the three-dimensional temperature field of the flame. The initial three-dimensional temperature field of the flame is obtained by initializing the temperature field based on the boundary grid of the three-dimensional temperature field of the flame, and a system matrix is ​​established based on the boundary grid of the three-dimensional temperature field of the flame. The elements in the system matrix represent the contribution weight of each grid cell to the absorption integral of each laser path. The initial three-dimensional temperature field of the flame is then projected forward through the system matrix to obtain the projection data. Based on the data of each laser path, a diagonal weighted matrix is ​​constructed, and the diagonal elements in the diagonal weighted matrix are set according to the signal-to-noise ratio of the corresponding laser path; based on the boundary mesh of the three-dimensional temperature field of the flame, the temperature gradient distribution characteristics and temperature smooth distribution characteristics of the flame are obtained, and a hybrid regularization function that integrates the temperature gradient distribution characteristics and temperature smooth distribution characteristics is constructed. Based on the projection data, diagonal weighted matrix, and hybrid regularization function, a temperature field objective function is constructed. The temperature field objective function is solved by an iterative optimization algorithm until the change in the three-dimensional temperature field between two adjacent iterations is less than a preset threshold, and the reconstructed three-dimensional temperature field of the flame is obtained.

[0007] Preferably, the generation function of the boundary mesh of the three-dimensional temperature field of the flame is expressed as: ; in: Represents the physical prior field; Indicates the mesh generation operator; Indicates a point in space Grid size at the location; This represents a parameter that controls the minimum grid size; in, The value represents a point in space The expected temperature change is drastic, especially at the flame boundary. Large value, in uniform air Small value; in For regions with large values, generate fine meshes. To capture steep gradients; in Larger grids are generated for regions with small values. To adapt to smooth areas.

[0008] Preferably, the acquisition of the projection data includes: The initial three-dimensional temperature field of the flame is obtained by initializing the temperature field based on the boundary mesh of the three-dimensional temperature field of the flame. And establish the system matrix based on the boundary grid of the three-dimensional temperature field of the flame. ; The initial three-dimensional temperature field of the flame Through system matrix Perform forward projection to obtain projection data .

[0009] Preferably, the construction of the diagonal weighted matrix includes: In the multiple laser paths formed by the scanning flame after the laser emitted by the diode laser is received by the photodetector, the amount of information carried by different laser paths and the degree of interference are different. The path passing through the core area of ​​the flame has strong signal absorption and high signal-to-noise ratio, while the laser path passing through the edge of the high-temperature smoke or affected by smoke scattering has weak signal and low signal-to-noise ratio. Based on the signal data and signal-to-noise ratio data of each laser path, a diagonal weighted matrix is ​​constructed. The diagonal weighted matrix diagonal elements According to the The signal-to-noise ratio (SNR) of each laser path is set, with low SNR laser paths assigned low weights and high SNR laser paths assigned high weights.

[0010] Preferably, the hybrid regularization function that integrates the temperature gradient distribution characteristics and the temperature smooth distribution characteristics is expressed as: ; in: This indicates the edge preservation option, set to... Norm penalty; This indicates the background smoothing option, set to... Norm penalty; and This represents the spatial difference operator, used to calculate the gradient of the temperature field in the horizontal and vertical directions; express Norm; express The square of the norm; This represents the weighting parameter, used to control... Smoothing terms relative to The strength of marginal terms; in, It indicates The sum of the absolute values ​​of the norms has a sparse distribution characteristic, corresponding to the region of the flame boundary temperature gradient distribution; It indicates The sum of the squares of the absolute values ​​of the norm has a smooth distribution characteristic, corresponding to a region where the temperature is evenly distributed inside and outside the flame.

[0011] Preferably, the objective function of the temperature field is expressed as: ]}; in: Represents the three-dimensional temperature field of a flame; Represents the regularization parameter; Represents the measured flame projection data vector; Represent the objective function of the temperature field; This represents the current three-dimensional temperature field; This indicates the search for a specific three-dimensional temperature field. This makes the objective function of the temperature field The value reaches its minimum.

[0012] This invention also provides a system for synergistic fire suppression using cryogenic and acoustic methods, comprising a sensing layer, a decision-making layer, and an execution layer; The sensing layer includes a smoke alarm device, an infrared detection device, and multiple tunable diode lasers and corresponding photodetectors; The decision-making layer includes a fire extinguishing parameter module and a central control unit. The fire extinguishing parameter module implements the steps of a three-dimensional temperature field reconstruction method for low-temperature and acoustic fire extinguishing as described above, based on the data measured by the sensing layer, and reconstructs the three-dimensional temperature field of the flame. It also obtains the optimal fire extinguishing acoustic parameters and low-temperature parameters based on the three-dimensional temperature field of the flame. The central control unit sends the optimal fire extinguishing acoustic parameters and low-temperature parameters to the execution layer. The execution layer includes a mobile positioning system, a cryogenic execution module, and an acoustic execution module. The cryogenic execution module and the acoustic execution module respectively receive optimal fire extinguishing acoustic parameters and cryogenic parameters. The mobile positioning system carries the cryogenic execution module and the acoustic execution module, calculates the fire extinguishing position of the cryogenic execution module and the acoustic execution module according to the optimal fire extinguishing acoustic parameters and cryogenic parameters, and moves the mobile positioning system to the front of the fire source according to the calculated fire extinguishing position. The system then works in concert with the fire source based on the optimal fire extinguishing acoustic parameters and cryogenic parameters to achieve coordinated fire extinguishing.

[0013] This invention also provides an electronic device, including a memory and a processor; The memory is used to store computer programs; When the processor executes the computer program stored in the memory, it implements the steps of a three-dimensional temperature field reconstruction method for cryogenic and acoustic fire suppression as described above.

[0014] This invention also provides a computer-readable storage medium for storing a computer program, which, when executed by a processor, implements the steps of a three-dimensional temperature field reconstruction method for cryogenic and acoustic fire suppression as described above.

[0015] This invention provides a three-dimensional temperature field reconstruction method for combined cryogenic and acoustic fire suppression, which has the following advantages compared with the prior art: This invention first constructs a physical prior field using prior information about the flame boundary acquired by an infrared thermal imager, and automatically adjusts the mesh size accordingly. The mesh is automatically densified in regions with severe temperature gradients, such as the flame boundary, and automatically thinned out in regions with uniform air. This physically guided non-uniform adaptive mesh generation first matches the three-dimensional temperature field boundary mesh with dynamic temperature gradient changes. Then, by constructing a weighted matrix based on path signal-to-noise ratio (SNR), higher reconstruction weights are assigned to paths with high SNR. This ensures that reliable data is emphasized and noise data is ignored during the iterative solution process, avoiding interference from smoke scattering, turbulence, and other disturbances. Artifacts or errors appear in the temperature field under the influence of the sound. At the same time, in the iterative inversion and reconstruction, a hybrid regularization function is designed to fuse the temperature gradient distribution characteristics and the temperature smooth distribution characteristics of the flame. This function takes into account the temperature gradient distribution characteristics, which represent the rapid temperature change at the flame boundary, and the temperature smooth distribution characteristics, which represent the uniform temperature distribution characteristics of the air region inside and outside the flame, in the inversion and reconstruction. In other words, the unique large gradient structure and smooth background structure of the flame temperature field are fully applied in the inversion. Finally, a high-precision three-dimensional temperature field of the flame is reconstructed to calculate the precise amount of cryogenic medium applied and the design amount of acoustic parameters to achieve high-precision coordinated fire extinguishing. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the fire extinguishing process provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the overall process of a three-dimensional temperature field reconstruction method for combined low-temperature and acoustic fire suppression, provided by an embodiment of the present invention. Figure 3 This is a schematic diagram of the execution system architecture for a three-dimensional temperature field reconstruction method applied to the combined low-temperature and acoustic fire suppression system, provided in an embodiment of the present invention. Detailed Implementation

[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0018] Currently, for fire protection in fields such as data centers, precision instruments, and cultural heritage sites, inert gas (such as IG-541) fire extinguishing systems are mainly used to achieve the effect of no secondary pollution. Although clean, these systems are complex, costly, and their speed in suppressing open flames needs improvement. Acoustic fire extinguishing, as an emerging technology, uses sound pressure to disturb the flame combustion zone, periodically pushing the flame away from the combustible material and interfering with the heat cycle between the flame and fuel to extinguish the fire. It has advantages such as reusability, low cost, and relatively simple equipment, but its main bottlenecks are effective range, energy efficiency, and the high power required for practical applications. Cryogenic technology (such as liquid nitrogen) is often used for rapid cooling, but its efficiency may be insufficient and its cost high when used alone for fire extinguishing, making it difficult to directly extinguish flames through cooling. Therefore, at present, temperature field imaging of the flame is used to control various fire extinguishing parameters of cryogenic and acoustic waves during fire extinguishing, in order to achieve efficient synergistic fire extinguishing.

[0019] Traditional solutions typically rely on passive infrared thermal imagers, which infer temperature by measuring radiation intensity. This approach is susceptible to interference from flame radiation and smoke. Furthermore, traditional infrared thermal imagers can only generate a two-dimensional temperature field. For fire areas with large temperature gradients, they cannot accurately construct a three-dimensional temperature field for the air near the flame side along the sound propagation path. This makes it difficult to determine the degree of application of the cryogenic medium in the combined cryogenic and acoustic fire suppression technology. The gain in fire suppression effect is uncontrollable. In some cases, the system may even consider the application of the cryogenic medium insufficient, leading to a reduction in acoustic power and thus failing to extinguish the fire. This poses a significant engineering problem.

[0020] To address the problems of traditional solutions, this invention integrates a "tunable laser absorption spectral tomography system" into the fire extinguishing platform. Specifically, multiple tunable diode lasers and corresponding photodetectors are arranged in different directions around the speaker side of the acoustic fire extinguishing device, forming a laser beam cross-scanning network. An infrared thermal imager is also equipped on the front and sides at an angle greater than 45° for auxiliary monitoring. The principle is that the lasers emit laser light of a specific wavelength to scan the absorption lines of temperature-sensitive gas molecules (such as water vapor H2O in the air). After the laser light passes through the area to be measured, it is received by the detector. Figure 1 and Figure 2 As shown, the specific implementation steps include: Step S1: Obtain the path integral absorptivity; for each laser path, by measuring the attenuation of the laser intensity, the integral value of the target gas absorptivity along that path can be obtained; this set of integral data constitutes the "projection" of the tomographic reconstruction; this method does not directly measure temperature, but rather inverts temperature by measuring the absorption of a specific wavelength of laser by the gas; its basis is the Beer-Lambert law of laser absorption spectroscopy, expressed as: .

[0021] Step S2: Three-dimensional field reconstruction (tomography); This invention utilizes an optical tomography algorithm to reconstruct a two-dimensional concentration distribution image of the target gas within the test area from the large amount of "line integral" projection data obtained above; directly using the general algebraic reconstruction algorithm (ART) is indeed difficult to meet the extreme requirements of speed, accuracy, and stability for acoustic fire extinguishing; addressing the core physical characteristic of "a huge temperature gradient at the interface between flame and air," this invention designs a novel reconstruction algorithm, specifically including: Step S201: Physically guided non-uniform adaptive mesh generation; define the mesh generation function as follows: .

[0022] in: This is a physical prior field, a three-dimensional function whose value represents a point in space. The "expected drastic temperature change" at the flame boundary is calculated from information such as the flame boundary and gradient priors provided by sensors like infrared thermal imagers; at the flame boundary... Large value; in uniform air, Small value; This represents the mesh generation operator, which is a function that incorporates physical priors. Mapped to grid size That is, at a point in space Grid size at the location; This is a parameter that controls the minimum mesh size to prevent the mesh from being subdivided infinitely.

[0023] In the above formula, the mesh size is a physical prior. The system will, based on the function, Values ​​are automatically adjusted: Regions with large values ​​(such as flame boundaries) generate smaller values. (Fine grid) to capture steep gradients; in For regions with small values, larger grids are generated to save computation; this achieves "on-demand allocation" of computing resources, fundamentally improving the accuracy and efficiency of large gradient field reconstruction.

[0024] Step S202: Construct the system matrix and initialize it.

[0025] Step S203: Iterative solution (core loop) (1) Forward projection process: The currently estimated temperature field is projected onto the forward projection process. Through system matrix Perform forward projection to obtain estimated projection data. .

[0026] (2) Introduction of a weighted matrix based on path sensitivity: In the acoustic fire extinguishing scenario, different laser paths carry different amounts of information; the path passing through the core of the flame has strong signal absorption and a high signal-to-noise ratio; while the path that only passes through the edge of the high-temperature smoke has a weak signal and is easily affected by noise; the general algorithm treats all path data equally, and the reconstruction result is easily contaminated by noise paths; therefore, this invention does not directly solve for the path sensitivity. Instead, it transforms it into an optimization problem, searching for a solution that optimizes the objective function. Minimum solution (i.e., temperature distribution); this process seeks the optimal balance between data fitting (making the solution conform to the measured values) and prior constraints (making the solution conform to physical intuition), and the objective function is expressed as: .

[0027] in: It is a diagonal weighted matrix, whose diagonal elements According to the Signal-to-noise ratio (SNR) setting for each laser path; It is a regularization function; introduced by a weighting matrix, paths with high signal-to-noise ratio are given higher weights, making them have a greater impact on the final result in reconstruction; this makes the algorithm more trusting of those measurements that pass through areas with clear signals (such as high-temperature core areas) when solving the problem, while automatically weakening the influence of those paths with weak signals and severe interference from smoke scattering, which significantly improves the anti-interference ability and robustness of the reconstruction results.

[0028] (3) Iterative reconstruction of physical constraints with prior knowledge of smoothness: The spatial smoothness of the temperature field is used as prior knowledge and added to the iterative objective function through regularization. For the specific "large gradient + smooth background" environment of acoustic fire extinguishing, the following hybrid regularization function is customized: .

[0029] in: For edge preservation terms ( punish), This is the background smoothing option. punish); and It is a spatial difference operator used to calculate the gradient of the temperature field in the horizontal and vertical directions; for Norm (sum of absolute values) The norm has "sparseness", which allows for a small number of large gradients (i.e. sharp temperature changes) in the solution, which corresponds exactly to the boundary of the flame; for The square of the norm (sum of squares) penalizes all large gradients and tends to produce a globally smooth solution, which corresponds to a uniform region inside and outside the flame. For weight parameters, control Smoothing terms relative to The strength of edge items; this design combines two different prior knowledge points: "edge preservation" and "background smoothing"; This ensures that sharp flame boundaries (large gradients) can be reconstructed. The term ensures that the temperature field outside the flame region is smooth. This "piecewise smoothing" prior model is specifically designed for large gradient temperature fields (such as the flame-air interface), unlike the traditional model that only pursues overall smoothness (Tikhonov regularization, which only contains...). The method described in this invention differs fundamentally from the method described in the previous one; therefore, the algorithm of this invention optimizes and updates the objective function based on the above physical constraints; the complete objective function is shown below: ]}.

[0030] (4) Convergence judgment and three-dimensional temperature field distribution Output.

[0031] Step S3: Verification of the two-dimensional temperature field of the infrared thermal imager; the infrared thermal imagers integrated on the acoustic fire extinguishing device detect the corresponding two-dimensional temperature fields in different directions, and compare them with the three-dimensional temperature field obtained in step S2. If the deviation is within an acceptable range, proceed to step S4; otherwise, update the flame boundary. The data is returned to step S2 for calculation.

[0032] Step S4: Quantitative and precise application of cryogenic medium based on the cryogenic medium dosage calculation model; obtaining the three-dimensional temperature field. Subsequently, the amount of cryogenic medium used is no longer an empirical value, but is precisely calculated through a physical model: .

[0033] in: It is the total heat (in units) that needs to be removed. ); and These are the densities of air (units). ) and specific heat capacity (unit) ); The target temperature to which it is expected to be cooled (unit: ) ); Integral domain It is the volume of the air zone to be cooled (unit: This formula calculates the amount of air within the target area. Cooling from the current temperature to the target temperature How much heat needs to be removed in total? ;get Then, the specific calculations can be performed based on the physicochemical properties of the selected cryogenic medium. For example, when liquid nitrogen is used as the cryogenic medium, considering the heating process after vaporization, the applied mass can be calculated using the following formula, expressed as: .

[0034] in: Latent heat of vaporization (unit) ); Heating a unit mass of cryogenic medium to Required calories (units) ).

[0035] like Figure 3 The diagram shows the system architecture of this invention during fire extinguishing. The system includes a perception layer, a decision layer, and an execution layer. The perception layer includes a smoke alarm and analysis device 1 and an infrared detection device 2, used to acquire fire data such as flame location, height, temperature, and type of combustible material. The decision layer is a central control unit 3, which has a pre-stored three-dimensional temperature field reconstruction method and can calculate the optimal fire extinguishing acoustic parameters and low-temperature parameters based on the data measured by the perception layer. The execution layer includes a mobile positioning system 4, a low-temperature execution module 5, and an acoustic execution module 6. The mobile positioning system 4 is used to carry and accurately position modules 5 and 6. The central control unit 3 sends the optimal low-temperature parameters and acoustic parameters to the low-temperature execution module 5 and the acoustic execution module 6 respectively based on the data received from the perception layer, and simultaneously controls the mobile positioning system 4 to move in front of the fire source 7. The low-temperature execution module 5 and the acoustic execution module 6, carried by the mobile positioning system 4, work together to act on the fire source 7 according to the parameters. The infrared detection device 2 continuously monitors the status of the fire source 7 and feeds it back to the central control unit 3, forming a closed-loop control.

[0036] This invention achieves a leap from "empirical spraying" to "model-based precise control" of cryogenic media through precise delivery and control of extinguishing energy. This avoids the "extinguishing failure" caused by insufficient dosage or the "resource waste" and "overcooling" caused by excessive dosage in traditional methods. The invention's solution is a complete "perception-decision-execution" intelligent system, whose weighted matrix... and dedicated regularization functions The algorithm design enables the system to automatically identify high-reliability data and adapt to the complex temperature distribution of fire scenes with "large gradient + smooth background". It can adapt to changes in fire conditions (such as flame movement and scale changes) and dynamically adjust the optimal parameters, demonstrating a high degree of intelligence and robustness.

[0037] The three-dimensional temperature field reconstructed by this invention can clearly reveal the temperature changes of the flame in the depth direction, and identify the precise location and temperature value of the flame core area, transition area, and peripheral flue gas area. At this time, the cryogenic medium is precisely delivered to the interface between the flame core area and the fuel bed to maximize the cooling effect. At the same time, the sound waves push the flame away from the fuel bed at the flame-air interface, and the cryogenic medium exchanges heat with the hot air at the flame-air interface, which significantly improves the adaptability and economy of the fire extinguishing strategy.

[0038] This invention first precisely constructs the three-dimensional temperature field of the flame. By precisely applying a low-temperature medium to the air near the flame side along the sound propagation path, a local low-temperature environment (below 15°C) is created, significantly reducing the temperature of the air participating in heat exchange. According to thermodynamic principles, the heat exchange rate is proportional to the temperature difference: as the temperature difference between the low-temperature air and the high-temperature fuel bed increases, the amount of heat exchange per unit time increases linearly. Experiments have verified that, under 15°C conditions, the oscillation response amplitude of the flame to 50-100Hz sound waves is increased by more than 25%, the critical acoustic particle velocity required for fire extinguishing is reduced by more than 20%, and the average fire extinguishing time is shortened by more than 30% at the same acoustic particle velocity.

[0039] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A three-dimensional temperature field reconstruction method for combined cryogenic and acoustic fire suppression, comprising arranging multiple tunable diode lasers and corresponding photodetectors in different directions of the combined fire suppression device, wherein the diode lasers emit laser light to scan the flame and the light is received by the photodetectors, characterized in that, The reconstruction method includes the following steps: Infrared thermal imagers are used to collect and fit the two-dimensional temperature field of a flame to obtain prior information of the flame boundary. Based on the prior information of the flame boundary, a physical prior field characterizing the degree of drastic change in flame temperature is constructed. According to the physical prior field, non-uniform adaptive meshing of the three-dimensional temperature field of the flame is performed to obtain the boundary mesh of the three-dimensional temperature field of the flame. The initial three-dimensional temperature field of the flame is obtained by initializing the temperature field based on the boundary grid of the three-dimensional temperature field of the flame, and a system matrix is ​​established based on the boundary grid of the three-dimensional temperature field of the flame. The elements in the system matrix represent the contribution weight of each grid cell to the absorption integral of each laser path. The initial three-dimensional temperature field of the flame is then projected forward through the system matrix to obtain the projection data. Based on the data of each laser path, a diagonal weighted matrix is ​​constructed, and the diagonal elements in the diagonal weighted matrix are set according to the signal-to-noise ratio of the corresponding laser path; based on the boundary mesh of the three-dimensional temperature field of the flame, the temperature gradient distribution characteristics and temperature smooth distribution characteristics of the flame are obtained, and a hybrid regularization function that integrates the temperature gradient distribution characteristics and temperature smooth distribution characteristics is constructed. Based on the projection data, diagonal weighted matrix, and hybrid regularization function, a temperature field objective function is constructed. The temperature field objective function is solved by an iterative optimization algorithm until the change in the three-dimensional temperature field between two adjacent iterations is less than a preset threshold, and the reconstructed three-dimensional temperature field of the flame is obtained.

2. The three-dimensional temperature field reconstruction method for combined low-temperature and acoustic fire suppression according to claim 1, characterized in that, The generation function of the boundary mesh of the three-dimensional temperature field of the flame is expressed as: ； in: Represents the physical prior field; Indicates the mesh generation operator; Indicates a point in space Grid size at the location; This represents a parameter that controls the minimum grid size; in, The value represents a point in space The expected temperature change is drastic, especially at the flame boundary. Large value, in uniform air Small value; in For regions with large values, generate finer meshes. To capture steep gradients; in Larger grids are generated for regions with small values. To adapt to smooth areas.

3. The three-dimensional temperature field reconstruction method for combined cryogenic and acoustic fire suppression according to claim 1, characterized in that, The acquisition of the projection data includes: The initial three-dimensional temperature field of the flame is obtained by initializing the temperature field based on the boundary mesh of the three-dimensional temperature field of the flame. And establish the system matrix based on the boundary grid of the three-dimensional temperature field of the flame. ; The initial three-dimensional temperature field of the flame Through system matrix Perform forward projection to obtain projection data .

4. The three-dimensional temperature field reconstruction method for combined cryogenic and acoustic fire suppression according to claim 3, characterized in that, The construction of the diagonal weighted matrix includes: In the multiple laser paths formed by the scanning flame after the laser emitted by the diode laser is received by the photodetector, the amount of information carried by different laser paths and the degree of interference are different. The path passing through the core area of ​​the flame has strong signal absorption and high signal-to-noise ratio, while the laser path passing through the edge of the high-temperature smoke or affected by smoke scattering has weak signal and low signal-to-noise ratio. Based on the signal data and signal-to-noise ratio data of each laser path, a diagonal weighted matrix is ​​constructed. The diagonal weighted matrix diagonal elements According to the The signal-to-noise ratio (SNR) of each laser path is set, with low SNR laser paths assigned low weights and high SNR laser paths assigned high weights.

5. A three-dimensional temperature field reconstruction method for synergistic low-temperature and acoustic fire suppression according to claim 4, characterized in that, The hybrid regularization function that integrates the temperature gradient distribution feature and the temperature smooth distribution feature is expressed as: ； in: This indicates the edge preservation option, set to... Norm penalty; This indicates the background smoothing option, set to... Norm penalty; and This represents the spatial difference operator, used to calculate the gradient of the temperature field in the horizontal and vertical directions; express Norm; express The square of the norm; This represents the weighting parameter, used to control... Smoothing terms relative to The strength of marginal terms; in, It indicates The sum of the absolute values ​​of the norms has a sparse distribution characteristic, corresponding to the region of the flame boundary temperature gradient distribution; It indicates The sum of the squares of the absolute values ​​of the norm has a smooth distribution characteristic, corresponding to a region where the temperature is evenly distributed inside and outside the flame.

6. A three-dimensional temperature field reconstruction method for combined cryogenic and acoustic fire suppression according to claim 5, characterized in that, The objective function for the temperature field is expressed as: ]}； in: Represents the three-dimensional temperature field of a flame; Represents the regularization parameter; Represents the measured flame projection data vector; Represent the objective function of the temperature field; This represents the current three-dimensional temperature field; This indicates the search for a specific three-dimensional temperature field. This makes the objective function of the temperature field The value reaches its minimum.

7. A system for synergistic fire suppression using low temperature and sound waves, characterized in that, include: The layers are: perception layer, decision-making layer, and execution layer. The sensing layer includes a smoke alarm device, an infrared detection device, and multiple tunable diode lasers and corresponding photodetectors; The decision layer includes a fire extinguishing parameter module and a central control unit. The fire extinguishing parameter module implements the steps of a three-dimensional temperature field reconstruction method for low-temperature and acoustic fire extinguishing as described in any one of claims 1 to 6 based on the data measured by the perception layer, and reconstructs the three-dimensional temperature field of the flame, and obtains the optimal fire extinguishing acoustic parameters and low-temperature parameters based on the three-dimensional temperature field of the flame. The central control unit sends the optimal fire extinguishing acoustic parameters and low-temperature parameters to the execution layer. The execution layer includes a mobile positioning system, a cryogenic execution module, and an acoustic execution module. The cryogenic execution module and the acoustic execution module respectively receive optimal fire extinguishing acoustic parameters and cryogenic parameters. The mobile positioning system carries the cryogenic execution module and the acoustic execution module, calculates the fire extinguishing position of the cryogenic execution module and the acoustic execution module according to the optimal fire extinguishing acoustic parameters and cryogenic parameters, and moves the mobile positioning system to the front of the fire source according to the calculated fire extinguishing position. The system then works in concert with the fire source based on the optimal fire extinguishing acoustic parameters and cryogenic parameters to achieve coordinated fire extinguishing.

8. An electronic device, characterized in that, include: Memory and processor; The memory is used to store computer programs; When the processor executes the computer program stored in the memory, it implements the steps of the three-dimensional temperature field reconstruction method for low-temperature and acoustic fire suppression as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, Used to store a computer program, which, when executed by a processor, implements the steps of a three-dimensional temperature field reconstruction method for cryogenic and acoustic fire suppression as described in any one of claims 1 to 6.

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